In general, a rotational body such as a door or a rotational cover or the like is rotatably provided on a housing or a main body through a hinge. There is a case that it is requested that the rotational body is to be kept at an arbitral angle. A torque hinge is used to respond to such a request, and it is configured so that when the rotational body is rotated, rotational resistance due to friction is caused.
For example, a torque hinge described in Patent Document 1: JP 4594135B includes two wing-shaped mounting members, a shaft member and two friction generating members. In each of the mounting members, a cylindrical portion is integrally provided. The cylindrical portions of the two mounting members are arranged along the same axial line, and the shaft member is inserted into the insides of these cylindrical portions. One end portion of the shaft member is fixed to the cylindrical portion of one of the mounting members. Both of the two friction generating members are formed into substantially annular shapes, and the shaft member is inserted into central holes and received in the cylindrical portion of the other mounting member. A shaft side friction generating member of the two friction generating members is rotated together with the shaft member. A cylindrical side friction generating member is rotated together with the other mounting member. The two friction generating members are pressure-contact with each other by mean of biasing force of a disk-shaped spring. Due to this pressure-contact, friction is caused between the friction generating members when the two mounting members are relatively rotated. With this friction, it is possible to keep a rotational body such as a door with respect to a main body at an arbitral relative rotational angle.
A cutout portion is formed at one position of a circumferential direction of the cylindrical portion of the other mounting member. In the cylindrical side friction generating member, a convex portion is formed so as to protrude radially and outwardly. This convex portion is fitted into the cutout portion. The width of the cutout portion is substantially the same as the width of the convex portion, and opposite end surfaces of the convex portion in a width direction are respectively in contact with opposite end surfaces of the cutout portion in the width direction. In this way, torque can be transmitted between the other mounting member and the cylindrical side friction generating member without play.